Air conditioning system



T 30, 1950 E. H. WHITE 2,509,948

AIR CONDITIONING SYSTEM Filed Nov. 25, 1946 3 SheetsSheet l A 4 INVENTOR EVERETT HAA/H TE ATTORNEY T l my 39, 1950 E. H. WHITE 2,509,948

AIR commoumc SYSTEM Filed Nov. 25, 1946 3 Sheets-Sheet 21 INVENTOR EVE RE T T H WH ITE ATTORNEY 3@, 1950 E. H. WHITE 2,509,943

' AIR counrrxonms SYSTEM Filed. Nov. 25, 1946 3 Sheets-Sheet 5 INVENTOR EVERETT H. WHITE ATTORN EY Patented May 30, 1950 UNITED STATES PATENT .OFFICE AIR CONDITIONING SYSTEM Everett H. White, St. Paul, Minn.

Application November 25, 1946, Serial No. 712,059

. Claims. 1

This invention has relation to an air conditioning system.

An object of the invention is to provide an air conditioning system which will include novel and improved mechanism through the instrumentality of which velocity and volume of air forced to and through a hood or plenum chamber of the air conditioning system can be progressively and accurately controlled and regulated through a selected range of values in response to the temperature in such hood or plenum chamber.

A further object is to provide an air conditioning system which will include a multiple speed drive for a fan or blower of the air conditioning system adapted to cause air to be forced to and through a hood or plenum chamber of said air conditioning system and a novel and improved construction and arrangement whereby the velocity and volume of air forced through said hood or plenum chamber can be progressively and accurately controlled and regulated through a selected range of values by adjustment of said multiple speed drive in response to the temperature in such hood or plenum chamber.

A further object is to provide an air conditioning system which will include amultiple speed drive for a fan or blower of the air conditionin system adapted to cause air to be forced to and through a hood or plenumchamber of said air conditioning system and a novel and improved construction and arrangement whereby the ve locity and volume of air forced to and through said hood or plenum chamber can be progressively and accurately controlled and regulated through sponse to changes in temperature of a heat responsive element of the air conditioning system.

A further object is to provide an air conditioning system which will include mechanism through the instrumentality of which the speed of rotation of a fan or blower of said air conditioning 1 2 blower selectively can be rendered operative and inoperative.

A further object is to provide in the air conditioning system various desirable and improved features and characteristics of construction which will be novel both as individual entities of said air conditioning system and in combination with each other. I

And a further objectis to provide an air conditioning system which will include features and characteristics of construction of thegeneral nae ture as hereinafter set forth. n

With the above objects in view, as well as others which will appear as the specification proceeds, the invention comprises. the construction, arrangement and combination of parts as now to be fully described and as hereinafter to be specii ically claimed, it being understood that the disclosure herein is merelyillustrative and intended in no way in a limiting sense, changes in details of construction and arrangement of parts being permissible so long as within the spirit of the invention and the scope of the claims which follow.

In the accompanying drawings forming a part of this specification:

Fig. 1 is a diagrammatic view of an air conditioning system in which the features and characteristics of theinvention are incorporated; Fig. 2 is an elevational view, with the cover of a casing of the air conditioning system removed, detailing parts of said air conditioning system under the control of a heat responsive element of the air conditioning system; Fig. 3 is a view, partially in elevation, partially in section and partially broken away, disclosing said heat responsive element, a furnace in which the heat responsive element is incorporated and some of the parts of the disclosure of Fig. 2

Fig. 4 is asectional view detailing mechanism of the air conditioning system through themstrumentality of which the speed of rotation of a fan or blower of said air conditioning system can be alterably controlled and regulated;

Fig. 5 isan end elevational View, on a reduced scale, of the mechanism disclosed in Fig. 4:, showing said mechanism as it would appear from the right side in said Fig. 4;

Fig. 6 is a detailsectional view, taken as on line 6-6 in Fig. 4;

Fig. 7 is a detail sectional view, on a reduced scale, taken as on line 11 in Fig. 4; and

Fig. 8 is a detail view of a modification.

With respect to the drawings and the numerals of reference thereon, ll] denotes a heating plant or furnace of common or preferred construction,

ll indicates a heater casing of the heating plant or furnace providing a hood or plenum chamber l2 in surrounding relation to a combustion chamber (not shown) of said heating plant or furnace adapted to be supplied with heating medium for an ordinary or preferred type of burner (not shown), l3 represents an outlet duct leading from said hood or plenum chamber, as, for example, to a space or room to be heated, l4 designates a blower for forcing air to and through the hood or plenum chamber l2 into the outlet duct 13, and [5 denotes an electric motor for actuating or driving the blower I4. v

The air conditioning system includes mechanism, denoted generally at l6, for a'lterablycontrolling and regulating operation of said blower l4 in response to changes in temperature of a heat responsive element I! of said air conditioning system.

The blower I4 is driven by the electric motor I5 through the medium of a belt it which rides aapulley I9. fixed upona driving shaft 29 for said blower and also rides a ,V-pulley 2| which is rigid with aself-oiling bushing 22 revoluble and slidable upon a shaft 23 driven by the electric motor I5.

The shaft 23 driven by said electric motor I5 includes a central opening 24, which extends longitudinally through said shaft 23, in the inner end portion of which the motor shaft 25 is adapted to be rigidly secured, as by a set screw 26, and the shaft 23 also includes an internal thread 2'l which bounds the outer end portion of .said central opening 24.

Said shaft 23 driven by the electric motor integrally supports an annular element 28, situated at the inner side of the V-pulley 2|, and an annular friction disc 29, in surrounding relation to the shaft 23, has a fiat inner surface thereof arranged in contiguous relation to a fiat outer surface of the annular element v28 disposed in a plane perpendicular to the axis of the shaft 23 and a flat outer surface thereof arranged in contiguous relation to a flat inner surface of the V-pulley 2| disposed in a plane perpendicular to said shaft 23. That is, the annular friction disc 29.is situated between the annular element 28 and the adjustable V-pulley 2|, It may befixed to either said annular element or to said V-pulley,.1but not to both.

A hollow fixture 39 is threadably received in the internal thread 2'! of the shaft 23 driven by the electricmotor l5, and said hollow fixture 39 is supported in bearing 3| situated in spaced relation to the electric motor I5. A casing of said electric motor is represented 32. More explicity, the hollow fixture 39 includes a reduced inner end portion 33 having an external thread 34 received by the internal thread 21 in such manner that an interior circumferential shoulder 35 of said hollow fixture is fitted-up against the adjacent end of the shaft 23, and the hollow fixture includes a reduced outer end portion 36 rotatably mounted in the bearing 3|. Said hollow fixture also includes an intermediate portion 31 of cross-sectional dimension as shown about. equal to the cross-sectional dimension of the reduced inner end portion 33. The hollow fixture 39 and parts rigid therewith are adapted to be rotated in the bearing 3!, and the construction and arrangement will be such that there will be no longitudinal movement of said hollow fixture relative to said bearing.

A block 38 of insulating material, situated at the outer side of the bearing 3!, is fixed, as

4 by screw bolts 39, to said bearing 3| up against washer situated between the bearing and said block 38.

A plurality of separate and independent bimetallic strips, each denoted 49 and of general U-shape, are supported in spaced apart relation to each other upon and about the hollow fixture 39. More explicitly, each of the lei-metallic strips 45 includes an outer arm 4| thereof which has its interior freeend portion 42 engaged against an annular shoulder 43, provided by an insulating block 44 fixed, as by a screw bolt 63, upon the intermediate portion 31 of the hollow fixture 3E], and situated" between said annular shoulder 43 and an-annular insulating member 45 fixed upon and perpendicular to the reduced outer end portion 36 of'saidhollow fixture. The construction...and arrangement will be such that the interior free end portions 42 of the outer arms M of .the lei-metallic strips 49 will be grasped and rigidly held between the annular shoulder43 and the annular insulating member 45. Each bimetallic .strip '40 also includes an inner arm 46 thereof which is situated in spaced, alined relation to the outer arm 4|, and the outer and inner arms 4| and 46 are integrally connected at the base 41 of each bi-metallic strip 49. Eachbase' His situated exteriorly of said outer and'inne'r' arms 4| and 46. An annular flange 48 upon the exterior margin of the annular insulating block 45 is as disclosed in spaced, overlying rela' tion to the bases 47 of the bi-metallic strips 40.

Spaced apart openings 49 through the annular insulating member 45, in spaced, surrounding relation to. the hollow fixture 39, are in adjacent relation to the outer arrns4lfof the bi-metalli'c strips 43, and a closure plate 59 for said spaced apart openings 49 is adjustably'supportedupon the outer surface of said annular insulating block 45. More explicitly, the closure plate 55 includes spaced apart, elongated, arc shape'slots 5! adapted to receive set screws 52ithreaded into the annular insulating block 45, andisaid closure plate also includes spaced apart openings 53 adapted to be alined or partially alined with the spaced apart openings 49in said annular insulating block. The construction and arrangement will be such that the closure plate 50 can'be'rotat ably adjusted relative to the annular insulating block 45 thus to adjust and regulate the sizes of passages for air, each constituted as'an opening 49"and'an opening 53, through said' closure plate and annular insulating block. The annular flange 43 rigidly supports spaced apart, interiorly situated fan blades 97 which are situated in adjacent relation to the inner arms 45" of the bi-metallic strips'43, at theside ofsaidbi-met'allic strips opposite the spaced apart openings' 49 and 53. An annular plate on the annular flange'48 at the inner sides of thefan'blades 91, or sides of said fan blades spaced from the annular insulating block 45, is denoted 98, .and said annular flange 48 is open at locations between and exterior to said fanblades 91.- As disclosedythe annular plate 98 is secured to the annular flange 48 by screw bolts 99. V

A resistance element54,jconstituted as resistance wire in mica, is suitably and conveniently supported, as at 55, upon the inner end of acontact screw 56 insulatively fixed within the hollow fixture 39 and is situated-between the'outer and inner arms 4! and- 490f the lei-metallic strips 40 in surrounding relation t'o said hollow fixture 39. Enamel-like, annular discs, denoted 51 and 58, respectively,-lie between the resistance wire in mica and the outer and inner arms 4| and 46 of the bi-metallic strips 40, in spaced, surrounding relation to the hollow fixture. The annular discs 51 and 5B are adapted to electrically insulate the resistance wire from the bi-metallio strips and, at the same time, permit heat from said resistance wire to be absorbed by said bimetallic strips. discs 5'! and 5B are electrical current resistors but not heat resistors.

The inner arm 46 of each bi-metallic strip 40 includes an interior free end portion 59 which is bent inwardly toward and alined with the self-oiling bushing 22, and the interiorfree end; portions 59 all lie in a, single circumference which is concentric to the shaft 23 driven by the electric motor I5. interior free end portions 59 all terminate in a single plane perpendicular to the axis of the shaft 23, and the bi-metallic strips 40 together constitute a thrust entity of the mechanism 16.

A thrust ring 6|, slidably situated upon an. outer end portion of the shaft 23 driven by the electric motor 15 between the interior free end portions 59 of the inner arms 46 of the bi-metallic strips it and the outer end of, theself-oiling bushing 22, is retained upon said .shaft,23 by the circumferential shoulder 35 provided by the hollow fixture 38 at the outer side of said thrust ring 6 l.

The electric motor 15 desirably is maintained in continuous operation when the temperature of air in the hood or plenum chamber i2 is at. or above a predetermined minimum temperature, as, for example, about 100 F., and devices, including the heat responsive element H, are present for rendering said electric motor It operative whenever temperature of air in said hood or plenum chamber at or above said predetermined minimum temperature exists and inoperative whenever temperature of air in the hood or plenum chamber below said predetermined temperature exists. The resistance element 54 is adapted to be energized by electric energy thus to cause the outer and inner arms 41 and 46 of the bi-metallic strips 4?], respectively, to become gradually Spaced farther and farther apart and the V-pulley 2|, the annular friction disc 29 and the annular element 28 to be clutched together, and the construction and arrangement are such that when the temperature of air in the hood or plenum,

chamber reaches said predetermined minimum temperature which causes the electric motor to bemade operative, or energized, pressure exerted bythe bi-metallic strips 41] upon the V.-pulley 2| is insufiicient to cause said V-pulley and the blower M to be operated. That is, said bi-metallic strips are adapted to exert no appreciable pressure against the thrust ring til at the time of starting up of the electric motor l5, so that the V-pulley 2!, the annular element 28 and the annular friction disc 29 will be under insufficient pressure to cause rotation of said V-pulley 2| and the blower driving shaft 20 to occur when the shaft 23 is set in operation in response to energization of the electric motor l5. Thus, said electric motor is adapted to be started up under no load. As the temperature rises in the hood or plenum chamber l2 after the electric motor.

15 is set in operation, said heat responsive element I1 is adapted to be actuated to .cause a circuit including the resistance element 54 to be closed thus to cause said resistance element to be energized. As the energized resistance element 54 causes the. bi-metallic strips 40 tobe Stated otherwise, said annular The inner free endsfill of said.

heated up, the outer and inner arms El audit of the separate and independent bi-metallic strips 40, respectively, become gradually spaced apart by progressively increasing heat applied to said bi-metallic strips, and the thrust ring 6| be comes actuated inwardly, toward the left in Fig. 4, thus to cause the V-pulley 2! to be moved toward the annular friction disc 29. and ;-the annular element 28. crease in pressure exerted by the bi-metallio strips 40 against the thrust ring El, the annular irictiondisc 29 is more tightly graspedbetween the V-pulley 2| and the annular element 28, and vice versa ;1 :As ithefriction between said V-pulley, annular .rfliCtiOIl, disc and annular element becomes great enough to cause the, V-pulley with the bushing 22 tobeturned in response to rotation of the shaft 23 driven by the electricmotor |,5,saidl,V-pul1ey, together with the hollowfixture 3B and parts rigid therewith, is rotated thus to ,causethe blower drivingshaft 20/00 her-.0 tatedthrough the medium of the. belt J8; .Some slippage occurs between the annula friction disc 29 and the parts engaged with said annularLfric-r; tion disc throughout the entire range of blower In the illustrated embodiment of theinvention', the heat responsive elementifl is a bimetallic:

helix having :its outer end 64, secured to a tubular, memberifidfixed in'the wall of the, heating plant; or ifurnace l0 and itsinner end fifisccured-to a, rod 61 rotatablymountedin said tubular, meme. ber. Phe tubular member 65 includesa portion. 68 thereof situated at the outer side of the heating plant or furnace In which supports a casing 69, and .-the rodfil extends outwardly to position be.-' yond said portion 68. p 1 i i "An. actuator arm 70, extending downwardlywithin the casing 59, is fixed, at 'l,l,qto=the outer: end portion of the rod 61, and an elongated conducting -element 12, constituted as a bi-metallic blade of ordinary or preferred configuration, also extends downwardly within the casing 69 andis insulatively fixed, at 13, upon the outer end of said rod 61.. The elongated conducting element orbi-metallic blade 12 mm front of and in spaced relation to the actuator arm '10, and the lowerend portion 14 of said elongated conducting element or bi-metallic blade 12 extends to position below the lower end of said actuator arm 10. The lower end of the elongated conducting element or bi'-metallic blade 12 supports a contactor 15 adapted to be engaged with and disengaged from a fixed contact element 16 suitably and conveniently insulatively supported on the casing 69.

An electric switch 11, at the side of the actuator arm 10 opposite the fixed contact element 16, is suitably and conveniently mounted within the casing 69 in spaced relation to said actuator arm. The electricswitch ll includes a fixed contact element 18 and a movable contact element 19 which is spring pressed toward said fixed contact element 18.

A resistance element 80, for supplying heat to the elongatedconducting element or bi-metallic. blade 12, has one of its ends 8| conductively connected to said elongated conducting element or bi-metallicblade and its other end 82 insulativee 1y associated with said elongated conducting element orl bi-metallic blade. Theconstruction andi Stated otherwise, with in;

of the blower can be increased from zero speed to maximum speed, and decreased from maximum Speed to zero speed, in any interval of time which may be selected. It is obvious that the time period will depend upon various factors surrounding the bi-metallic strips 40, the resistance element 54, etc., and the characteristics of the electrical energy employed. By way of example, an installation inherently can include provision for increase of speed of the blower employed from zero speed to maximum speed in three minutes, more or less.

The construction and arrangement including the spaced apart openings 49 and 53, the fan blades 91, etc., obviously constitutes means through the instrumentality of which increase of speed of rotation of the blower in any interval of time which may be predetermined can be accurately controllably accomplished. Desirably, the electric motor 15 can be a substantially constant speed motor. The motor driven shaft 23 and the parts rigid with said motor driven shaft, including a force unit consisting of the bi-metallic strips 40, the resistance element 54, the hollow fixture 30, the insulating block 43, the annular insulating block 45 and its fan blades 91, etc., are assembled with the electric motor shaft 25 to b continuously rotated at the speed of said motor shaft at all times while the electric motor is in operation. The construction and arrangement will be such that air will be drawn or sucked by the fan blades 91 through the spaced apart openings 49 and 53 over the bi-metallic strips 40 and radially out of the unit constituting the mechanism It at the side of said bi-metallic strips 40 opposite said spaced apart openings 49 and 53. It will be evident that b adjustment of the closure plate thus to adjust and regulate the sizes of the passages for air through said closure plate and the .annular insulating block 45, by way of the spaced apart openings 49 and 53, the temperature within the mechanism la in surrounding relation to the bi-metallic strips 40 can be kept at any substantially constant value which may be selected. The

smaller the sizes of the passages for air, the higher the temperature constantly maintained at the location of and about the lei-metallic strips, and the larger the sizes of said passages for air, the lower the overall temperature at and about said bimetallic strips.

Save for the resistance element 80, the contactor 15 and the fixed contact element l6 normally would remain engaged at all times when the temperature of air in the hood or plenum chamber i2 is at or above the temperature at which said contactor 15 and said fixed contact element 16 became engaged. In the disclosure as made, the resistance element Bil becomes energized the instant the contactor l5 and the fixed contact element it become engaged. Al-

most immediately after encrgization of said resistance element 80, the elongated conducting element or lei-metallic blade 12 becomes warped, in response to absorption of heat from the resistance element 80, to cause the contactor 15 to be moved in direction away from the fixed contact element 16, toward the left in Fig. 2 of the drawings. Immediately upon breaking of the electric circuit which includes said resistance element 80, by separation of said contactor 15 and fixed contact element '16, the resistance element 8!] becomes de-energized. A very short time after de-energization of the resistance element 86, the elongated conducting element or bimetallic blade 12 becomes warped, in response to dissipation of heat, to cause the contactor 15 to be moved in direction toward the fixed contact element 16. Assuming the furnace temperature in the meantime to be rising, the heat responsive element I1 will have caused said elongated conducting element or bi-metallic blade 12 to be swung bodily slightly in direction toward said fixed contact element 76 while the resistance element 80 remained de-energiz ed. In short order, the contactor l5 and the fixed contact element 16 again will become engaged with the same result as above described. After several, or a number of, repeated energizations and deenergizations of said resistance element 88 have occurred the heat responsive element I I will have swung the elongated conducting element or bimetallic strip 12 bodily in direction toward the fixed contact element 16 through a distance too great to permit the resistance element 80, even though energized, to warp said elongated con ducting element or bi-metallic blade 12 to sunlcient extent to cause thecontactor 15 and the fixed contact element 16 to become disengaged. When this condition occurs, the resistance element 54 constantly will remain energized. In practical operation, the net result will be that the contactor T5 and the fixed contact element 16 will remain engaged for very short intermittent periods of time, thus to cause the resistance element 54 to be energized for very short intermittent periods of time, when the temperature in the hood or plenum chamber I2 is at or close to the temperature intended to cause said contactor I5 and fixed contact element to become engaged, will remain engaged for increasingly longer intermittent periods of time, to cause said resistance element 54 to be energized for increasingly longer periods of time, as the temperature in said hood or plenum chamber rises, and will remain constantly engaged, to cause the resistance element 54 to be constantly energized, when the temperature in said hood or plenum chamber is considerably above said temperature intended to cause the contactor T5 and fixed contact'element '6 to become engaged. The action as described will cause the bi-metallic strips 411 to become evenl and uniformly heated. While the temperature in the hood or plenum chamber is rising in response to firing up of the'heatlng plant or furnace burner, the bi-metallic strips an will be receiving heat intermittently in increasing quantities from the resistance element 54 and the heat applied to said bi-metallic strips will have opportunity to become evenly and uniformly distributed to and about all of the bimetallic strips thus to render them capable of quite efficiently and satisfactorily accomplishing their intended service during the time they are causing the blower to be speeded up. The intermittent application of heat to the bi-metallic strips 40 is provision for relatively low average temperature of said lei-metallic strips, and, consequently, relatively low fan speed during the time of warming up of the furnace. The bi,- metallic strips 40 have body and weight much greater than the body and weight of the resist.- ance element so that said bi-metallic strips will lose their heat much moreslowly than will said resistance element 80. When the temperature in the hood or plenum chamber dictates continuous driving of the blower at the speedof the electric motor I5, so that the V-pulley 2| is rigid with the motor driven shaft. 23, the bimetallic strips 40 will be receiving heat incon- -stantquantity from=said resistanceelement 54.

Immediately when the temperature of air in the hood or plenum =chamber-l2 starts to fall, due to. cessation of operation of the heating -plantlor furnaceburner, or for-anyother reason, the contactor 15 will havetendenc tocommence to recede: and become disengaged from :the. fixed contactielement l5 thus eventually to cause both of 'theresistanceelements. 54 and 8!! to be deener- 'gized. Said resistance elementsat once will begin tocool on and the outer and inner arms ii and 46 of the bi-metallic strips to will. simultaneously begin to move-toward each other thus eventually to cause or permit the ."-pu1ley- .2! to-be released. The blower M will cease operating when the temperature in the hood or plenum chamber which caused said contactor and the fixed contact element lfi to become engaged and said I 2 falls just below the temperature blowerrto become operative.

' In Fig. 8 of the drawings, an elongated oonduct ing element 112", constituted as a bi metalli'c blade equivalentto the bi-metallic. blade '52, includes a contactor 15 adapted 'to engage-contacts of a rheostat l 01. Said rheostat til-i is connected to lead -wire 94 adapted to extend to the secondary of a-transformersuch as 85, and-said elongated conducting element 12" is connectedto a lead wire'fill" adaptcdto extend to aterminal such as 9L The action of an air conditioning system made according to the invention and including a rh'eostat arranged as in Fig. 8; of course in en of a resistance elementsuch as tllarranged'as in Figs. 1and'2, obviously will' cause heat in increasing quantities to be applied to a resistance element such as 54'vvith rise of "temperature in a hood or plenum chamber. It will be evident that swinging movement of the elongated conducting ele- 'ment-'!'2 toward the right in Fig. 8 will progressively reduce resistance of the rheostat l ill thus to causepotential'appli'ed'to a resistance element such" as 54 to be increased No matterwhatmay be th'e actual temperature inthe hood or plenum chamber 12', or whether the heating plant orfurnace I'Oi's heating up or cooling on; operation of the blower I 4 will be in response to temperature of air in said hood or plenum chamber. The velocity and volume of air forced toand through the hood or plenum chamber-will be progressively and accurately controlled and'regulated through a selected range of-values, predetermined by the construction and arrangement of the-bimetallic strips M the resistance element 54, etc., etc, and the electricalenergy employed, by adjustment of the multiple speed from air in motion as it'travels throughthe hood or plenum chamber past-said heat responsive element: The heat responsive element or bimetallic helix is required to perform functions which are quite simpleand necessitate but little effort or power.

Tlreprinciples of the invention are. applicable to various types of air heating and cooling systems'.

Whatis claimedxis:

1. In an air conditioning system, a .blowenaa drivingzshaft, an element rigid withsaid shaft, a drive interposed between said element and-said blower. for causing'the blower to be actuatedat variable speeds in response to actuationof said shaft at constant speed, said drive including mechanism in spaced relation to said element adaptedlto be expanded in-response to rise'of temperature to causesaid blower to be actuatedat higherspeedsand to be contracted in resp'onseto fall of temperature to cause the blower to be'actuated at' lower speeds, resistance means for causing said'mechanism to be heated, and a circuit *for causing said'resistance means selectively. to be energized and de-energized.

2? In an air conditioning system, a blower, a driving shaft; an element rigid with said shaft, a friction drive upon saidshaft between said element andsaid blower, mechanism fixed upon said shaft in spaced relation to said element adapted to beexpanded in response to rise of temperature to operatesaid friction drive 'to cause said blower to be actuatedat higher speeds and to be contracted in response to fall of temperature to operate the friction drive to cause the blower to be actuated at lower speeds, resistance means fixed to rotate with said shaft for causing said mechanism tohe -heated, anda circuit for causing said resistance means selectively to be energizedand deenergized.

3. In an air conditioning system,- a blower, s. driving shaft, a first clutch element'rigid with said shaft, a second'clutch element freely rotatable upon said shaft, a drive interposed between said secondclutch element and said blower, mechanism fixed upon said shaft at the side of said second clutch element opposite said first clutch element adapted to be expanded in response to rise of temperature to operate said second clutch element into engagement with said first clutch element to cause said blower tobeactuatedat higher speeds and to be contracted in response to fall of temperature -to release the second clutch element from the first clutch element to cause the blower to be actuated at lower speeds, re'sistance means fixed to rotate with said shaft for causing said mechanism to be heated, and a circuit for causing said resistance means'selectively to be energized and deenergized.

4. In-an air conditioning system, a blower, a driving shaft, an element'rigid withsaid shaft, a friction drive upon said shaft between said element and said blower, mechanism fixed upon said shaft in spaced relation to said element adapted to be'expandedv in response to rise of temperature to operate said friction,driveto causesaid. blower to be actuated at higher speeds and to be contracted in response to fall of temperature to operate the friction drive to cause the blower to be actuated at lower speeds, resistance means fixed'to rotate with said shaft for causing said mechanism to be heated, a circuit for causing said resistance means" selectively to be energized and deenergi'zed, and means for causing air'in predetermined amount constantly to travel pastsaid mechanism and said resistance means.

5; In an air conditioning system, a blower, a driving shaft; a first clutch element rigid with said shaft, a second clutch element freely rotatable upon said shaft, a drive interposed between said second clutch element and said blower, mecha-nism fixed upon said shaft at the side of said secand clutch element opposite-said first clutclr ele- 13 ment adapted to be expanded in response to rise of temperature to operate said second clutch element into engagement with said first clutch element to cause said blower to be actuated at higher speeds and to be contracted in response to fall of temperature to release the second clutch element from the first clutch element to cause the blower to be actuated at lower speeds, resistance means fixed to rotate with said shaft for causing said mechanism to be heated, a circuit for causing said resistance means selectively to be energized and deenergized, and means including adjustable air passages and fan blades rotatable with said shaft for causing air in predetermined amount constantly to travel past said mechanism and said 15 resistance means.

EVERETT H. WHITE.

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